After a long break from WoW I recently came back and leveled a DK. I didn't pursue any professions while leveling the toon so he has nothing at 85. I figured I could level professions while in the queue or when I don't have much time to be at my computer.
I wanted to go with Mining/Blacksmithing...but a buddy of mine says to go with a gather/gather setup because the gear offered by 4.1 (and beyond) will outpace the gear blacksmiths can create.
I've gone gather/gather since TBC and tired of it. I would rather have at least one production profession...